This invention relates to improvements in label applying machinery.
All previous and presently known machinery for applying pressure sensitive labels to an article use the same kind of carrier web for the labels, and the same kind of label removing method.
The conventional carrier web consists of a series of labels with a viscous (pressure sensitive) adhesive applied to a carrier strip of paper which has been coated on the label supporting side with a release agent. The labels are spaced along the strip, and the unneeded waste (or matrix) from which the labels have been die cut is always removed during manufacture.
The labels are removed sequentially by pulling the carrier strip around a relatively sharp edge under tension. The label, because of its stiffness, releases from the carrier web and continues in a straight line over the edge rather than bend sharply and follow the carrier web.
This established method has a number of drawbacks:
(1) The need to remove all the waste or matrix from between and around labels during manufacture, because its presence tends to hold labels in place during peeling,
This waste removal requirement makes the labels cost much more, because it limits the printing and die cutting speed severely and because a great deal of costly extra material has to be added around each label to make the ladderlike waste strip strong enought to remove by pulling it free after die cutting on a printing press.
(2) The label peeling process used in all previous labelling machines requires pulling the web under high tension over a relatively sharp edge. Tiny cuts or nicks caused by the die cutting and slitting weaken the web and it frequently breaks, especially at high speed.
(3) Small invisible interruptions in the release coating are common. Through them the label adhesive is able to adhere strongly to the unprotected carrier web. When this occasionally occurs at the leading edge of a label, it will not peel but will follow the carrier strip around even a sharp edge. The same can happen when the adhesive is cold, or too old.
(4) The need for great stiffness in the label material prevents the use of many desired materials such as plastics, or very thin labels, or very soft and pliant labels.
(5) During the peeling process, labels are being projected beyond the peeling edge and are essentially unsupported, except occasionally on one side (opposite the adhesive). They are easily disturbed and deflected by small irregularities, tramp particles of adhesive, air currents, or static electricity.
(6) The means of actually applying the labels varies, including a blast of air (inaccurate at any distance and does not apply labels firmly), a roller (inaccurate), and a plunger (too rigid and destructive on moving products).
(7) Automatic labelling machinery is very costly, partly because of sophisticated electronic label sensing and web control systems within the labeller.
It should be appreciated therefore that a label carrying arrangement and apparatus for applying labels therefrom to goods, which permits the use of very thin and soft labels as well as stiffer labels, which permits the use of lower cost label strips, and which permits label application at higher speeds and with greater reliability than presently known systems would be most desirable.